Light sensitive quinoline diazo compounds



United States Patent Ofiice 3,297,443 Patented Jan. 10, 1967 This invention relates to novel diazo compounds and to their use in diazotype photoprinting processes.

In the diazotype photoprinting process, a transparent or translucent original which is to be copied is placed in contact with paper or other material coated with a formulation containing a diazo compound and then exposed to light emission between the 360 A. and 4200 A. and, more particularly, between the 3000 A. and 4000 A. lines. Such rays effectively decompose the diazo component which they touch so that it can no longer combine with a coupling component to form a dye. Accordingly, when a diazotype layer is exposed to the source of light, the diazo compound decomposes to leave a colorless copy in those areas not protected by the opaque images on the transparent or translucent original. The diazo compound decomposes with the formation of nitrogen and colorless compounds, usually phenol. The diazo compound in the area beneath the opaque images of the original document later, in a development step, reacts with a coupling agent and thereby results in a visible image on the copy.

In one embodiment the present invention relates to a diazotype photoprinting material comprising a light-sensitive material coated with a 6-(N-substituted-1,2,3,4-tetrahydroquinoline diazonium chloride.

In a specific embodiment the present invention relates to a diazotype photoprinting paper comprising a lightsensitive paper coated with 6-(N-isopropyl-1,2,3,4-tetrahydroquinoline)diazonium chloride zinc chloride salt.

It is believed that the 6-(N-substituted-1,2,3,4-tetrahydroquinoline)diazonium chloride is a new composition of matter and, accordingly, is being claimed as such in the present application. It also is believed that the corresponding zinc chloride salt is a new composition of matter and this, likewise, is being claimed as such herein. In addition, the corresponding diazonium salts of other halides and the other metal halide salts thereof are believed to be new compositions of matter and accordingly these other salts likewise are being claimed as such in the present application.

In one embodiment the novel diazo compound of the present invention is a 6-(N-substituted-1,2,3,4-tetrahydroquinoline)diazonium chloride. The substitution attached to the nitrogen atom of the heterocyclic ring may comprise any suitable group and may be selected from alkyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, aryl, aralkyl, alkaryl, etc. In one preferred embodiment the alkyl substituent is a secondary alkyl group. Illustrative compounds in this embodiment include 6- N-isopropyl l ,2,3,4-tetrahydroquinoline diazonium chloride,

6- (N-sec-butyl- 1 ,2,3 ,4-tetrahydroquinoline diazonium chloride,

6- (N-sec-pentyl-1,2,3,4-tetrahydroquinoline diazonium chloride,

6- (N-sec-hexyl- 1 ,2,3,4-tetrahydroquinoline diazonium chloride,

6- (Nsec-heptyl- 1,2,3 ,4-tetrahydroquinoline diazonium chloride,

6- (N-sec-octyl-l ,2,3 ,4-tetrahydroquinoline diazonium chloride,

6- (N-sec-nonyl- 1 ,2,3,4-tetrahydroquinoline diazonium chloride,

6- (N-sec-decyl-1,2,3,4 tetrahydroquinoline)diazonium chloride,

6- N-sec-undecyl- 1 ,2,3,4-tetrahydroquinoline) diazonium chloride, I

6- N-sec-dodecyl- 1 ,2,3 ,4-tetrahydroquinoline diazonium chloride, etc. I

In another embodiment the alkyl substituent is 21 normal alkyl group. Illustrative compounds is this embodiment include 6- N-methyl- 1 ,2,3,4-tetrahydroquinoline) diazonium chloride,

6-(N-ethyl-1,2,3,4-tetrahydroquinoline diazonium chloride, a Y

6- (N-n-propyl-1,2,3,4-tetrahydroquinoline diazonium chloride, 7

6-(N-n-butyl-1,2,3,4-tetrahydroquinoline) diazonium chloride,

6- N-n-pentyl- 1 ,2,3,4-tetrahydroquinoline) diazonium chloride,

6- N-n-hexyl- 1 ,2,3 ,4-tetrahydroquinoline diazonium chloride,

6- N-n-heptyl- 1 ,2,3,4-tetrahydroquinoline) diazonium chloride, 1

6-(N-n-octyl-1,2,3,4-tetrahydroquinoline) diazonium chloride,

6- (N-n-nonyl-1,2,3,4-tetrahydroquinoline diazonium chloride,

6- (N-n-decyl- 1 ,2,3 ,4-tetrahydroquin-oline) diazoniu chloride, 7

6-(N-n-undecyl- 1 ,2, 3 ,4-tetrahydro quinoline)diazonium chloride,

6- (N-n-dodecyl- 1 ,2,3,4-tetrahydroquinoline diazonium chloride, etc.

In still another embodiment, the alkyl substituent is a tertiary alkyl group. Illustrative compounds in this embodiment include 6- N-t-butyl- 1 ,2,3,4-tetrahydroquinoline) diazonium chloride,

6- N-t-pentyll ,2,3,4-tetrahydroquinoline) diazonium chloride,

6- (N-t-hexyl-1,2,3 ,4-tetrahydroquinoline diazonium chloride, 1

6- (N-t-heptyl- 1 ,2,3,4-tetrahydroquinoline diazonium chloride,

6-(N-t-octyl1,2,3,4-tetrahydroquinoline diazonium chloride,

6- (N-t-nonyl- 1 ,2,3 ,4-tetrahydroquinoline diazonium 1 chloride,

6- (N-t-decyl- 1,2,3 ,4-tetrahydroquinoline diazonium chloride,

6- (N-t-undecyl-l ,2,3,4-tetrahydroquin-oline diazonium chloride,

6- N-t-dodecyl- 1 ,2,3 ,4-tetrahydroquinoline diazonium chloride, etc.

When the substituent attached to the heterocyclic nitrogen atom includes a cycloalkyl group (cycloalkyl, cycloalkylalkyl or alkylcycloalkyl), illustrative compounds include 6- (N-cyclopropyl- 1,2, 3,4tetrahydroquinoline) diazonium chloride,

6- (N-cyclobutyl- 1,2, 3 ,4-tetrahydroquinoline diazonium chloride,

6-(N-cyclopentyl-1,2, 3 ,4-tetrahydroquinoline diazonium chloride,

6- (N-cyclohexyl- 1 ,2, 3 4-tetrahydro quinoline) diazonium chloride,

6- Ncycloheptyl- 1 ,2, 3 ,4-tetrahydroquinoline diazonium chloride,

6- N-anthracyl-l ,2, 3 ,4-tetrahydroquinoline diazonium chloride,

6- (N-alkylanthracyl-l ,2,3,4-tetrahydroquinoline diazonium chloride,

6- (N-dialkylanthracyl- 1,2, 3,4 tetrahydroquinoline) diazonium chloride,

6-(N-trialkylanthracyl-l,2,3,4-tetrahydroquinoline)diazonium chloride,

6- (N-naphthylalkyl-l ,2,3,4-tetrahydroquinoline) diazonium chloride,

6- N -anthracyl alkyl-1 ,2,3,4-tetrahydroquinoline) diazonium chloride, etc.

From the above description, it will be seen that the present invention comprises a number of different novel compounds. It is understood that these different compounds are not necessarily equivalent in their light-sensitive properties. In another embodiment the invention contemplates the corresponding diazonium salts of the other halides including the iodide, bromide and fluoride, as well as mixtures thereof. It is understood that these other halide salts Will correspond to the chloride salts specifically set forth hereinbefore.

In a preferred embodiment, the 6-(N-substituted-1,2,3,4- tetrahydroquinoline)diazonium halide is used in association with a metal halide salt which improves the stability of the diazo compound. Accordingly, in a particularly preferred embodiment, the diazo compound comprises a salt with a metal halide including zinc chloride, cadmium chloride, tin chloride, etc., as well as the corresponding bromides, iodides and/ or fluorides. Zinc chloride appears to offer particular advantages and accordingly an especially preferred diazo compound for use in the present invention is 6-(N-isopropyl-l,2,3,4-tetrahydroquinoline)diazonium chloride zinc chloride salt. The zinc chloride salt apparently .is present as a complex which also may be described as the one-half salt or as the double salt. The preferred diazo compound may be illustrated as follows:

It will be noted that the positions in the rings have been numbered in order to fully describe this compound. The exact structure of the diazo compound has not been definitely established, but is believed to be somewhat as illustrated above. However, it is understood that applicant does not intend to be limited to this specific structure but, as hereinbefore set forth, the structure shown above illustrates the probable configuration of a diazo compound of the present invention.

It is understood that one or both of the rings may contain one or more additional substituents attached thereto. In general, electron-donating or electron-withdrawing substituents in the proper position serve to increase the sensitivity of the diazo compound to U.V. light. In one embodiment the substituent is in the 8-position and in another embodiment is in the 5- or 7-positions. When two substituents are present, they preferably are in the 8- position or 5- and 7-positions. 'Any suitable electron-donating and withdrawing group or groups may be employed. In one embodiment the group is an oxygen-containing, electron-donating group (prefenably in the 8-position) and more particularly hydroxy and/ or alkoxy including methoxy, ethoxy, propoxy and butoxy, although the alkoxy group may contain a larger number of carbon atoms and thus may range up to decyloxy. The alkoxy group or groups may contain a hydroxy substituent to further improve the properties, including particularly water solubility.

In another embodiment the substituent attached to one or both of the rings is electron-withdrawing and is a halogen and preferably chlorine (particularly in the 5 and/or 7-positions). In still another embodiment the l or substituent is a hydrocarbon group (particularly in the 2- and/or 8-positions) and preferably an alkyl group selected from methyl, ethyl, propyl, butyl, pentyl and hexyl although, here again, higher molecular weight alkyl groups may be employed which usually will not contain more than about 12 carbon atoms each.

From the above description, it will be seen.- that the present invention includes a number of different metal halide salts preferably selected from those'specifically set forth hereinbefore. Here again, it is understood that these different metal halide salts are not necessarily equivalent in their light-sensitive properties.

The novel diazo compounds of the present invention are prepared in any suitable manner. For example, 6- (N sec-alkyl-1,2,3,4-tetrahydroquinoline)diazonium halides may be prepared by first forming N-sec-alkyl-1,2,3,4- tetrahydroquinoline preferably by the reductive alkylation of quinoline or 1,2,3,4-tetrahydroquinoline with a ketone at a temperature within the range of from about to about 250 C., more particularly from about to about 180 C., and a hydrogen pressure within the range of from about 10 to 100 atm. or more in the pres ence of a reductive alkylation catalyst. Any suitable reductive alkylation catalyst is used and may comprise a composite containing platinum, palladium, nickel, cobalt, molybdenum, etc., or mixtures thereof with a suitable carrier including alumina, silica, zirconia, titania, thoria, zinc oxide, or mixtures thereof. For example, N-isopropyl-1,2,3,4-tetrahydroquinoline is prepared by the reductive alkylation of quinoline or 1,2,3,4-tetrahydroquinoline with acetone. When N-n-alkyl-1,2,3,4-tetrahydroquinoline is desired, it is prepared in a similar reductive alkylation process but using an aldehyde instead of a ketone. When a tertiary alkyl substituent is desired, it may be obtained by reacting 1,2,3,4-tetrahydroquinoline with a tertiary alkyl halide, particularly tertiary alkyl iodide as, for example, tertiary butyl iodide, at a temperature within the range of from about 0 to about 30 C. followed by alkalinization, or preferably is obtained by first nitrating 1,2,3,4-.tetrahydroquinoline using equal volumes of concentrated sulfuric acid and concentrated nitric acid and then reacting the nitrotetrahydroquinoline with a tertiary alcohol in the presence of a suitable catalyst. For example, 6-nitro-1,2,3,4-tetrahydroquinoline is reacted with tertiary butyl alcohol in the presence of 85% phosphoric acid by gradually adding the alcohol to a mixture of the nitrotetrahydroquinoline and phosphoric acid at a temperature of 40-50 C. with intimate stirring and then heating the mixture to a temperature of 6080 C. N-Cycloalkyl-1,2,3,4-tetrahydroquinoline is prepared by reductive alkylation in substantially the same manner described above but using a cycloalkyl ketone. For example, N-cyclohexyl-l,2,3,4-tetrahydroquinoline is prepared by reductive alkylation of quinoline or 1,2,3,4-tetrahydroquinoline with cyclohexanone.

The N-substituted-1,2,3,4-tetrahydroquinoline is converted into the corresponding diazonium halide in any suit-able manner. For example, the diazonium chloride may be prepared by first forming the corresponding 6- amino derivative and then converting this to the diazonium chloride. In one method the 6-amino derivative is prepared by commingling the N-substituted-1,2,3,4-tetrahydroquinoline with hydrochloric acid at a temperature below about 10 C. and thus may range from 10 to 10 C. and preferably from 0 to about 8 C. A nitrosating agent is added at this low temperature, preferably in increments, with intimate stirring. Sodium nitrite is a preferred nitrosating agent. Nitrous acid or nitrous acid precursors may be employed including, for example, organic nitrites as ethyl nitrite, propyl nitrite, butyl nitrite, pentyl nitrite, etc. A reducing agent then is added and the mixture is heated to about 40-50" C. Any suitable reducing agent is employed, zinc being particularly preferred. Other reducing agents include cadmium, tin, iron, etc., and, in fact, any metal above hydrogen in the Electromotive Series of Elements. The reactants are stirred at the desired temperature for a time suflicient to obtain complete reaction, which time may range from 0.5 to 24 hours or more. When the metal halide is not desired in the product, the reaction mixture is subjected to alkalinization and the resulting inorganic insoluble hydroxides are removed by filtration. The precipitate then is washed free of amine with water, organic solvents such as methanol, ethanol, benzene, acetone, ether, etc., and the amine is recovered from the filtrate and washing by phase separation, ether or benzene extraction (if necessary) and distillation. The resulting 6-amino-N-substituted -l,2,3,4-tetrahydroquinoline is then converted to the diazonium chloride by further reaction with hydrochloric acid and sodium nitrite at the low temperature hereinbefore set forth. The 6-(N-substituted-1,2,3,4-tetrahydroquinoline)diazonium chloride is of limited stability and, therefore, should be protected from heat, light and air.

As hereinbefore set forth, another embodiment of the invention comprises the metal halide salt of the diazonium chloride. The metal halide salt is prepared in the same manner as described above except that zinc chloride or other metal halide is added to the reaction mixture, either originally or as a later step in the process. For economic reasons, the metal halide salt preferably comprises the metal halide desired in the final product. For example, when the zinc chloride salt is desired, zinc chloride is employed as the metal halide. In this embodiment alkalinization of the reaction mixture is not required and any excess metal is removed by filtration. The final product is separated in substantially the same manner as hereinbefore described. The examples appended to the present specification described various methods of preparing the novel compounds of the present invention.

For use in the diazo photoprinting process, the diazo compound of the present invention is employed in any suitable formulation. As hereinbefore set'forth, a diazo coupling agent is required in the process. The coupling agent has been broadly defined in the literature as a substance which bears an active or mobile hydrogen atom. Coupling agents include hydroxy derivatives of benzene such as resorcinol and phloroglucinol or of naphthalene such as alpha and beta-naphthols, their sulfonic acids and other substituted naphthols. Acetoacetyl, pyrozo: lones and other ketomethylene compounds also are used. Other constituents of the formulation depend upon the particular diazotype photoprinting process used and may include acids, wetting agents, pigments, binders, and one or more agents for protection against yellowing caused by alkaline oxidation, against light discoloration, against bleeding or running of the dye when moistened, and against feathering or running of subsequently applied ink. It is understood that all of these agents will be thoroughly compatible with each other and with the diazo compound of the present invention and the particular coupling agent employed. These components of the formulation are well known in the art and, in the interest of brevity, will not be described in detail herein because they do not comprise a novel feature of the present invention.

The light-sensitive material is coated with the formulation in any suitable manner and will depend upon the particular photoprinting process being employed. These photoprinting processes include the dry method, semi-dry method, wet method, solvent coating system, etc. In

these methods decomposition and coupling of the diazo compound is effected by light, heat, ammonia and/or other suitable methods. Here again, these methods are well known in the industry and, inthe interest of brevity, are not being described in detail in the present application because they do not comprise a novel feature thereof. However, it is understood that the particular formulation will be selected to meet the specific photoprintingprocess employed.

The order of applying the various ingredients to the paper or other material will depend upon the particular photoprinting process employed. In the dry method, the

paper or other material is first coated with the diazo compound, along with other components, as required, and

then coated with the coupling agent, along with other components, as desired. In this method, the diazo compound is decomposed during exposure to actinic rays. In the wet method, the diazo compound is first applied to the paper or other material and then is subjected to exposure to the light rays, after which it is passed through a solution of the coupling agent and other materials, to be followed by heating and drying. In the ammonia system, the paper or other material, after exposure, is contacted with ammonia vapors or wet ammonia. The solvent coating system is used particularly for printing on Mylar or other suitable plastic material.

It is understood that a mixture of diazo compounds may be used to form reproductions of new or different colors. When desired, a mixture of coupling agents also may be used.

The following examples are introduced to illustrate further the novelty and utility of the present invention but not with the intention of unduly limiting the same.

EXAMPLE I The diazo compound of this example is 6-(N-isopropyll,2,3,4 tetrahydroquinoline)diazonium chloride zinc chloride salt and was prepared as follows. N-isopropyl- 1,2,3,4-tetrahydroquinoline was prepared in the first step by the reductive alkylation of quinoline with acetone at 160 C. and atm. initial hydrogen pressure in the presence of a platinum-alumina catalyst. The N-isopropyl- 1,2,3,4-tetrahydroquinoline g.) was dissolved in 393 ml. concentrated hydrochloric acid and 585 ml. of water. The mixture was stirred while cooling to 40 C. and resulted in a clear solution. To this solution was added 49.2 g. of sodium nitrite dissolved in 162 ml. of water gradually over a period of 4 hours while at the low temperature. The low temperature was obtained by placing ,the mixing zone in an ice bath. After further stirring,

the solution was allowed to remain at room temperature overnight and then 137 ml. of concentrated hydrochloric acid was added, followed by the gradual addition of 114 g. of zinc dust at room temperature with intimate stirring. The mixture then was heated to 40 C. for three hours, followed by filtration under vacuum and water washing, and the filtrate then was alkalinized with 20% sodium hydroxide solution in order to obtain the 6-amino compound in pure form so that it could be definitely identified. The mixture then was filtered to remove zinc hydroxide, washed with benzene to remove occluded product from the zinc hydroxide, and the liquid solutions were dried over sodium sulfate, distilled to remove benzene and fractionated under reduced pressure. About 40 g.

of overhead boiling at 116-1l8 C. at 0.5 mm. were recovered, which material crystallized on cooling. The crystals had a melting point of 60 'C. and a neutralization equivalent of 99, which corresponds to the theoretical neutralization equivalent of 95, calculated for 6- amino N isopropyl 1,2,3,4-tetrahydroquinoline. The product was further identified by nuclear magnetic resonance spectroscopy.

The 6 amino-N-isopropyl-l,2,3,4-tetrahydroquinoline was converted to the diazonium chloride zinc chloride salt by dissolving the 6-amino-N-isopropyl-1,2,3,4-tetrahydroquinoline in 6 N hydrochloric acid (25 cc. of concentrated hydrochloric acid in 10 cc. of water), chilled in an ice bath to about 0 C. and, at this temperature, 8.2 g. of sodium nitrite in 8 cc. of water were added with intimate stirring. In order to destroy excess sodium nitrite, 1 g. of urea was added to the mixture. To the mixture then was added 6.3 g. of zinc chloride as a 50% aqueous solution, with continuous stirring, following which the mixture was diluted with 200 cc. of acetone and v filtered to remove the precipitate, the filtrate evaporated under vacuum to remove acetone and the residue was dried in a desiccator. 6-(N-isopropyl-1,2,3,4-tetrahydroquinoline)diazonium chloride zinc chloride salt was recovered as a dark viscous oil in an amount of 11 g. Identity of the product was established by subjecting the same to irradiation to UV. light and measuring the nitrogen liberated thereby.

EXAMPLE II Example I describes the stepwise preparation, including intermediate alkalinization. The present example describes a preparation in which the intermediate 6-amino derivative is not separated. In this preparation, N-isoproply-l,2,3,4-tetrahydroquinoline is dissolved in dilute hydrochloric acid at ice bath temperature and an aqueous solution of sodium nitrite is slowly added thereto, accompanied by intimate stirring for two hours, after which the mixture is allowed to stand overnight. The following morning, with the mixture at room temperature, concentrated hydrochloric acid is added, followed by the gradual addition of zinc dust accompanied with intimate stirring. The reaction is exothermic and is cooled to maintain a temperature of about 40-50 C. Excess zinc then is filtered off and the filtrate is cooled in an ice bath, after which additional hydrochloric acid is added and then a 25% aqueous solution of sodium nitrite is added thereto in incremental portions. The reaction mixture is stirred for an additional one-half to one hour and urea is added to decompose excess sodium nitrite. Carbon black is stirred into the mixture to absorb by-products, after which the reaction mixture is filtered and the filtrate treated to recover the 6-(N-isopropyl- 1,2,3,4-tetrahydroquinoline)diazonium chloride zinc chloride salt by conventional means including salting out with sodium chloride, evaporating to remove water, fractionation, etc.

EXAMPLE III In the preparation described in Example II, zinc dust is added at an intermediate step in the preparation. In the preparation of this example, starting with 6-amino- N-isopropyl-1,2,3,4-tetra'hydroquinoline, zinc chloride is added before the diazotization. According to this method of preparation, 15 g. of zinc chloride are dissolved in 25 cc. concentrated hydrochloric acid and 15 cc. of water. To this mixture is added 0.1 mole of 6-amino-N-is'opropyl-1,2,3,4-tetrahydroquinoline and the mixture is chilled in an ice bath to about 2 C. Then 7.1 g. of sodium nitrite in 10 cc. of water is added with intimate stirring at the low temperature. Stirring is continued for about 0.5 to 1 hour, with the temperature being allowed to reach room temperature. At this point, 1 g. of urea is added with stirring, followed by the addition of 10 or more grams of sodium chloride in order to saturate the liquid with sodium chloride. The mixture then is chilled to about C. and, after settling, the aqueous phase is decanted ofi, dried by evaporation under vacuum, and the residue then is treated with methanol or acetone to dissolve the organic salt, following which the mixture is filtered and the filtrate is evaporated to dryness to recover the 6-(N-isopropyl-1,2,3,4-tetrahydroquinoline)diazonium chloride zinc chloride salt.

EXAMPLE IV nitrite, hydrochloric acid and zinc chloride in substantially the same manner as described in Example I. Following treatment with charcoal, dissolving in methanol and filtration, the filtrate was recovered as an aqueous solution containing 1.5% by weight of 6-(N-sec-butyl- 1,2,3,4 tetrahydroquinoline)diazonium chloride zinc chloride salt. Such a solution may be employed to coat paper for use in the diazotype photoprinting process and the product of this example accordingly was recovered in this manner.

EXAMPLE V The diazo compound of this example is 6-(N-isobutyl- 1,2,3,4-tetrahydroquinoline)diazonium chloride zinc chloride salt and was prepared in substantially the same manner as described in Example I. When starting with 57 g. of N-isobutyl-1,2,3,4-tetrahydroquinoline, a yield of 21 g. of 6-amino N isobutyl-1,2,3,4-tetrahydroq'uinoline was obtained as an oil having a boiling point of l24125 C. at 0.5 mm., an index of refraction, n of 1.576 and a neutralization equivalent of 104, which corresponds to the theoretical neutralization equivalent of 102. The 6- amino-N-isobutyl-1,2,3,4-tetrahydroquinoline, prepared in the above manner, then was converted to the diazonium chloride zinc chloride salt by reacting with hydrochloric acid, sodium nitrite and zinc chloride in substantially the same manner as described in Example I. 6-(N-isobutyl- 1,2,3,4-tetrahydroquinoline)diazonium chloride zinc chloride salt was recovered in a yield of 7.3 g. as a rusty brown solid. Here again, identity of the product was established by irradiation in U.V. light.

EXAMPLE VI The diazo compound of this example is 6-(N-n-butyl- 1,2,3,4-tetrahydroquinoline)diazonium chloride zinc chloride salt and was prepared in substantially the same manner described in Example I. N-n-butyl-l,2,3,4-tet-rahydroquinoline was prepared by the reductive alkylation of quinoline with n-butyraldehyde. When starting with 55 g. of N-n-butyl-1,2,3,4-tetrahydroquinoline, a yield of 24 g. of 6-arnino-N-n-butyl-1,2,3,4-tetrahydroquinoline was obtained as an oil having a boiling point of 126l27 C. at 0.3 mm., an index of refraction, 11 of 1.5777 and a neutralization equivalent of which corresponds to the theoretical neutralization equivalent of 102. The 6-amino N-n-butyl-l,2,3,4-tetrahydroquinoline then was reacted with hydrochloric acid, sodium nitrite and zinc chloride in substantially the same manner as hereinbefore described to prepare 6-(N-n-butyl-l,2,3,4-tetrahydroquinoline)diazonium chloride zinc chloride salt, which was recovered as an orange-brown solid. Here again, the identity was confirmed by irradiation in UV. light.

EXAMPLE VII The diazo compound of this example is 6-(N-cyclohexyl 1,2,3,4 tetrahydroquinoline)diazonium chloride zinc chloride salt. N-cyclohexyl-1,2,3,4-tetrahydroquinoline was prepared by the reductive alky'lation of quinoline with cyclohexanone. When starting with 60 g. of N-cyclohexyl-1,2,3,4-tetrahydroquinoline, a yield of 26 g. of 6-amino-N-cyclohexyl-1,2,3,4-tetrahydroquinoline was obtained as a liquid having a boiling point of 161 C. at 0.6 mm., an index of refraction, 11 of 1.598 and a neutralization equivalent of which corresponds to the theoretical neutralization equivalent of 115. The diazonium chloride zinc chloride salt was prepared in substantially the same manner described hereinbefore and 18 g. of 6 (N cyclo hexyl-l,2,3,4-tetrahy'droquinoline)diazonium chloride zinc chloride salt were recovered as an orange-brown spongy glass.

EXAMPLE VIII As hereinbefore set forth, one utility for the diazo compounds of the present invention is their use in the diazotype photoprinting process. 6-(N-isopropyl-1,2,3,4tetrahydroquinoline)diazonium chloride zinc chloride salt, prepared as described in Example I, was evaluated in this process. For comparative purposes, comparable runs were made using conventional type compounds.

Four separate formulations were prepared of substantially the same composition, except for the diazo compound. These formulations were of the following recipe: Table I Water cc 100 Urea g 20 Malonic acid g l Coupling agent 1 percent by weight 2 Diazo compound percent by weight- 2 1 2,3dil1ydr0.\'y-6-uaphthalene sulfonic acid sodium salt.

In formulation A, the diazo compound is p-morpholinobenzene diazonium chloride zinc chloride salt. In formulation B, the diazo compound is p-dimethylaminobenzenediazonium chloride zinc chloride salt. In formulation C, the diazo compound is p-diethylaminobenzenediazonium chloride zinc chloride salt. In formulation D, the diazo compound is 6-(N-isopropyl-l,2,3,4-tetrahydroquinoline)- diazonium chloride zinc chloride salt. It will be noted that formulations A, B and C utilize conventional diazo compounds and that formulation D utilizes a diazo compound of the present invention. A

Each of the formulations were used to separately coat separate sheets of paper. The coated papers then were used in a photoprinting process of the dry method in which the sheets of paper each were placed in contact with an original document containing printing and then were exposed to actinic light and subsequently heated at about 232 C. The exposure times required to obtain identical prints were measured and reported in seconds. The time required when using the morpholino derivative was assigned an arbitrary value of 1 as representative of the prior art, and the times required using the other diazo compounds to obtain identical prints were then calculated as a ratio thereto. This, then, describes the speed of the printing when using the different diazo compounds. These results are reported in the following table:

Table II Formulation: Ratio of speed A 1.0 B 1.2 C 1.3 D 2.5

From the data in the above table, it will be seen that the diazo compound of the present invention resulted in a formulation which was from 2 to 2.5 times as fast as the diazo compounds presently being used. This is an important improvement in the diazo photoprinting art because it avoids the objection to this type of process of requiring too long a time to obtain copies. Obviously this makes the process much more attractive and improves its commercial acceptance.

EXAMPLE IX The diazo compounds, prepared as described in Examples IV, V, VI and VII, also were used to coat paper for reproduction in the manner described in Example VIII. All of these diazo compounds were decomposed upon exposure to actinic light and subsequent heating at about 232 C.

I claim as my invention:

1.. A light-sensitive printing material coated with 6-(N- sec-alkyl-l,2,3,4-tetrahydroquinoline)diazonium chloride metal chloride salt.

2. A light-sensitive printing material coated with 6-(N- isopropyl-1,2,3,4-tetrahydroquinoline) diazonium chloride zinc chloride salt.

3. A light-sensitive printing material coated with 6-(N- sec-butyl-1,2,3,4-tetrahydroquinoline) diazonium chloride zinc chloride salt. Y

4. A light-sensitive printing material coated with 6-(N- sec-alkyl-l,2,3,4-tetrahydroquinoline diazonium chloride zinc chloride salt.

5. 6 (N sec-alkyl-1,2,3,4-tetrahydroquinoline)diazonium halide.

'6. 6 (N isopropyl-1,2,3,4-tet'rahydroquinoline)diazonium chloride.

7. 6 (N sec-alkyl-l,2,3,4-tetrahydroquin'oline)diazonium chloride.

S. 6 (N sec-alkyl-l,2,3,4-tetrahydroquinoline)diazonium halide metal halide salt.

9. 6 (N sec-alkyl-l,2,3,4-tetrahydroquinoline)diazonium chloride zinc chloride. salt..

10. 6 (N isopropyl 1,2,3,4-tetrahydroquinoline)diazonium chloride zinc chloride salt.

References Cited by the Examiner UNITED STATES PATENTS 3/1939 Schmidt et al. 96-91 3/1961 Baril et a1. 96-49 

1. A LIGHT-SENSITIVE PRINTING MATERIAL COATED WITH 6-(NSEC-ALKYL-1,2,3,4-TETRAHYDROQUINOLINE)DIAZONIUM CHOLRIDE METAL CHLORIDE SALT. 